Knackstedt & Näther, Knackstedt & Co.

Knackstedt & Näther started in Munich in 1898, though Näther didn't last long and the the firm soon moved to Hamburg, operating as photographers and printers. It grew rapidly, too rapidly, and in 1911 became bankrupt and was re-founded as Knackstedt & Co, which lasted until the 1960s. The studio parted and ran on under the K&N name until 1919. The TPA site has extensive details of this firm, and there is an article in the German Wikipedia.

Knackstedt & Näther evidently had a logo of conjoined K and N, though the cards I have seen, view cards and stereographs, lack this and bear the full name.

Verlag Waldemar Heldt was a publisher in Hamburg which among other things published books of photographs. Lotte Herrlich (1883-1956) was a photographer who in the 1920s specialized in pictures of children and in nudism and the new naturism movement. The card of a girls head, part of a series, is in effect promoting one of her books. Heldt published this card and Knackstedt printed it.